V3.1

This is the start of a PullRequest for v3.1

v3.1 will switch MvvmCross to a new profile

@Cheesebaron has done some fab work recently documenting the profiles - 
https://docs.google.com/spreadsheet/pub?key=0AgHEgqqaasTkdDVMQWNURUNhSUdlZzV0Z2p3djlLQ3c&single=true&gid=3&output=html

@dsplaisted has made some interesting comments on http://stackoverflow.com/questions/19997784/are-there-any-pros-to-using-pcl-profile-158-over-78-for-xamarin-and-mvvmcross

To complete this pull request we need to:

[ ] choose a new profile - 78 or 158?
[ ] make any code changes needed for that profile (e.g. for reflection apis)
[ ] transfer all the PCL projects to that profile
[ ] transfer all the WinPhone project over to WP8
[ ] update all the samples and N+1s
[ ] update the Wiki

Would love to do this soon... perhaps aim for the next 7 to 14 days

Beyond this, now we will definitely have async/await available I'd love to start getting some async/await plugins done (e.g. file, network and sqlite)